I'm hosting a network with 40 hubs and 7000 online players, this happens when too much player are logged on the network and generate an important traffic between lobby<>gameserver.

The bungee loadbalance all the players on this lobbys depending of the count.

I have huge lag spike with TPS drop, the asyncChatEvent is frozen too, I've tried to get timings > http://timings.aikar.co/?url=9762387
Not usefull the main threads seem blocked

So I've installed yourkit and began to profile, when this happen all the netty are blocked...

The cpu was fine (see attachement), but the 4 netty thread are blocked...

For information when this happened the server had something like 50 players on and the 4 other spigot instance 20 to 30 players on.

The only "thing" that is common in this issue is then it happen when we reach enough online players (6500) to have a high traffic between lobby<>gameserver.

If i have 5000 online and 100 players on the same 5 lobby hosted on the same server there's no problem... so maybe something happen with the asyncPreLoginEvent Is use to load players datas...

Attached > the screens and the snapshot from yourkit.